1. Field of the Invention
The present invention relates generally to a multi-band antenna, and more particularly to a small-size patch antenna.
2. Description of the Prior Art
Since the wireless communication technology of using electromagnetic wave to transmit signals has the effect of remote device transmission without cable connection, and further has the mobility advantage, the technology is widely applied to various products, such as moveable phones, notebook computers, intellectual home appliance with wireless communication features. Because these devices use electromagnetic wave to transmit signals, the antenna used to receive electromagnetic wave also becomes a necessity in the application of the wireless communication technology. In present electronic devices, antennas always be assembled inside the electronic devices to make the appearance of the device beauty. Since the limit of the inner space of the electronic device, the height and size of antenna will be restricted. Patch antennas, as a kind of antenna, has small height. TW Patent No. 587847 disclosed a small-size multi-band patch antenna referencing to FIG. 1. The patch antenna comprises a signal element 21′ having a plate 211′ extending from a bar 42′ and a plate 212′ extending from the bar 42 opposite to a plate 211′, a grounding element 22′ tabulated and parallel to the signal portion 21′, a resonant cavity 231′ produced by a space formed between the signal element 21′ and the grounding element 22′ and at least a metal slip 43′ with a proper length and bending to form a long piece 431′ and a short piece 432′. The long piece 431′ is parallel to the grounding element 22′. The antenna has two feeding point respectively on the long piece 431′ and the signal element 21′. A extending section 41′ extends from the signal element 21′ to regulate the impedance matching. So the structure of the antenna is complex. TW Patent No. 284088 discloses a multi-band invert-F patch antenna. The antenna uses a grounding portion assembly which connects to a grounding element to regulate the impedance matching to ensure enough band width of the antenna. The additional grounding portion makes the structure complex. Besides, the antenna needs to be assembled on an insulative substrate, therefore, it may be not fit for the inner space of the electronic device.
Hence, an improved antenna is desired to overcome the above-mentioned shortcomings of the existing antennas.